Revert of Revert of [Easy Unlock] Port the BluetoothConnectionFinder class to native code.

Revert of Revert of [Easy Unlock] Port the BluetoothConnectionFinder class to native code. (patchset #1 id:1 of https://codereview.chromium.org/651073002/)

Reason for revert:
I believe that the original revert was incorrect, so relanding the change.

Original issue's description:
> Revert of [Easy Unlock] Port the BluetoothConnectionFinder class to native code. (patchset #4 id:320001 of https://codereview.chromium.org/633253002/)
>
> Reason for revert:
> Causes compile failure on mac:
> http://build.chromium.org/p/chromium.mac/builders/Mac%20Builder%20%28dbg%29/builds/75518
>
> Original issue's description:
> > [Easy Unlock] Port the BluetoothConnectionFinder class to native code.
> >
> > A couple of pieces are left as TODOs for future CLs:
> >   * Porting the "seek device by Bluetooth address" feature.
> >   * Wiring up a screen lock state accessor.
> >
> > BUG=420946
> > TEST=components_unittests
> > R=tengs@chromium.org
> >
> > Committed: https://crrev.com/ac4df1c4df6fdc7c771eb0bdeb15dbd6f2dbb98c
> > Cr-Commit-Position: refs/heads/master@{#299415}
>
> TBR=tengs@chromium.org,isherman@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=420946
>
> Committed: https://crrev.com/ab9f183ccbec50c1bfa42514019e089fccd9f0f4
> Cr-Commit-Position: refs/heads/master@{#299420}

TBR=tengs@chromium.org,yoichio@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=420946
Committed: https://crrev.com/16aaea49ad1966526b8d60ca29f59511bc30e78a
Cr-Commit-Position: refs/heads/master@{#299581}

[Ilya Sherman, 2014-10-14 23:15:20]

Created Revert of Revert of [Easy Unlock] Port the BluetoothConnectionFinder
class to native code.

[commit-bot: I haz the power, 2014-10-14 23:16:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/656963002/1

[commit-bot: I haz the power, 2014-10-14 23:18:13]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-14 23:19:20]

Patchset 1 (id:??) landed as
https://crrev.com/16aaea49ad1966526b8d60ca29f59511bc30e78a
Cr-Commit-Position: refs/heads/master@{#299581}